Turn health.h/health.c into a library
[lttng-tools.git] / src / bin / lttng-sessiond / health.h
1 /*
2 * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License, version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11 * more details.
12 *
13 * You should have received a copy of the GNU General Public License along with
14 * this program; if not, write to the Free Software Foundation, Inc., 51
15 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 */
17
18 #ifndef _HEALTH_H
19 #define _HEALTH_H
20
21 #include <assert.h>
22 #include <time.h>
23 #include <pthread.h>
24 #include <urcu/tls-compat.h>
25 #include <urcu/uatomic.h>
26 #include <urcu/list.h>
27
28 /*
29 * These are the value added to the current state depending of the position in
30 * the thread where is either waiting on a poll() or running in the code.
31 */
32 #define HEALTH_POLL_VALUE (1UL << 0)
33 #define HEALTH_CODE_VALUE (1UL << 1)
34
35 #define HEALTH_IS_IN_POLL(x) ((x) & HEALTH_POLL_VALUE)
36
37 struct health_app;
38
39 enum health_flags {
40 HEALTH_ERROR = (1U << 0),
41 };
42
43 struct health_state {
44 /*
45 * last counter and last_time are only read and updated by the health_check
46 * thread (single updater).
47 */
48 unsigned long last;
49 struct timespec last_time;
50
51 /*
52 * current and flags are updated by multiple threads concurrently.
53 */
54 unsigned long current; /* progress counter, updated atomically */
55 enum health_flags flags; /* other flags, updated atomically */
56 int type; /* Indicates the nature of the thread. */
57 /* Node of the global TLS state list. */
58 struct cds_list_head node;
59 };
60
61 /* Declare TLS health state. */
62 extern DECLARE_URCU_TLS(struct health_state, health_state);
63
64 /*
65 * Update current counter by 1 to indicate that the thread entered or left a
66 * blocking state caused by a poll(). If the counter's value is not an even
67 * number (meaning a code execution flow), an assert() is raised.
68 */
69 static inline void health_poll_entry(void)
70 {
71 /* Code MUST be in code execution state which is an even number. */
72 assert(!(uatomic_read(&URCU_TLS(health_state).current)
73 & HEALTH_POLL_VALUE));
74
75 uatomic_add(&URCU_TLS(health_state).current, HEALTH_POLL_VALUE);
76 }
77
78 /*
79 * Update current counter by 1 indicating the exit of a poll or blocking call.
80 * If the counter's value is not an odd number (a poll execution), an assert()
81 * is raised.
82 */
83 static inline void health_poll_exit(void)
84 {
85 /* Code MUST be in poll execution state which is an odd number. */
86 assert(uatomic_read(&URCU_TLS(health_state).current)
87 & HEALTH_POLL_VALUE);
88
89 uatomic_add(&URCU_TLS(health_state).current, HEALTH_POLL_VALUE);
90 }
91
92 /*
93 * Update current counter by 2 indicates progress in execution of a
94 * thread.
95 */
96 static inline void health_code_update(void)
97 {
98 uatomic_add(&URCU_TLS(health_state).current, HEALTH_CODE_VALUE);
99 }
100
101 /*
102 * Set health "error" flag.
103 */
104 static inline void health_error(void)
105 {
106 uatomic_or(&URCU_TLS(health_state).flags, HEALTH_ERROR);
107 }
108
109 struct health_app *health_app_create(int nr_types);
110 void health_app_destroy(struct health_app *ha);
111 int health_check_state(struct health_app *ha, int type);
112 void health_register(struct health_app *ha, int type);
113 void health_unregister(struct health_app *ha);
114 void health_init(struct health_app *ha);
115
116 #endif /* _HEALTH_H */
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